/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2008, Red Hat Middleware LLC or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Middleware LLC.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 *
 */
package org.hibernate.persister.entity;

import java.io.Serializable;

import org.hibernate.FlushMode;
import org.hibernate.HibernateException;
import org.hibernate.engine.EntityKey;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.impl.AbstractQueryImpl;
import org.hibernate.loader.entity.UniqueEntityLoader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Not really a <tt>Loader</tt>, just a wrapper around a
 * named query.
 * @author Gavin King
 */
public final class NamedQueryLoader implements UniqueEntityLoader {
	private final String queryName;
	private final EntityPersister persister;
	
	private static final Logger log = LoggerFactory.getLogger(NamedQueryLoader.class);

	public NamedQueryLoader(String queryName, EntityPersister persister) {
		super();
		this.queryName = queryName;
		this.persister = persister;
	}

	public Object load(Serializable id, Object optionalObject, SessionImplementor session) 
	throws HibernateException {
		
		if ( log.isDebugEnabled() ) {
			log.debug(
					"loading entity: " + persister.getEntityName() + 
					" using named query: " + queryName 
				);
		}
		
		AbstractQueryImpl query = (AbstractQueryImpl) session.getNamedQuery(queryName);
		if ( query.hasNamedParameters() ) {
			query.setParameter( 
					query.getNamedParameters()[0], 
					id, 
					persister.getIdentifierType() 
				);
		}
		else {
			query.setParameter( 0, id, persister.getIdentifierType() );
		}
		query.setOptionalId(id);
		query.setOptionalEntityName( persister.getEntityName() );
		query.setOptionalObject(optionalObject);
		query.setFlushMode( FlushMode.MANUAL );
		query.list();
		
		// now look up the object we are really interested in!
		// (this lets us correctly handle proxies and multi-row
		// or multi-column queries)
		return session.getPersistenceContext()
				.getEntity( new EntityKey( id, persister, session.getEntityMode() ) );

	}
}